|Publication number||US4954365 A|
|Application number||US 07/451,699|
|Publication date||Sep 4, 1990|
|Filing date||Dec 18, 1989|
|Priority date||Dec 18, 1989|
|Publication number||07451699, 451699, US 4954365 A, US 4954365A, US-A-4954365, US4954365 A, US4954365A|
|Inventors||Richard A. Neifeld|
|Original Assignee||The United States Of America As Represented By The Secretary Of The Army|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Referenced by (16), Classifications (11), Legal Events (10)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.
This invention relates to a method of preparing a thin diamond film
There has been a strong desire in the art to prepare diamond thin films. This has been due to the desirable physical properties of diamonds such as large band gap, high dielectric breakdown strength, high thermal conductivity, hardness, optical and ultraviolet transparency, and high electron mobility. Heretofore diamond films have generally been prepared by low vapor pressure non equilibrium growth techniques such as hot filament, glow discharge, chemical vapor deposition (CVD), and plasma enhanced CVD. These techniques, though capable of polycrystalline diamond thin film growth, are expensive due to the requirement of a vacuum chamber and the associate low throughput. Other drawbacks to these techniques include high power consumption and a high degree of process control.
The general object of this invention is to prepare diamond thin films. A more particular object of the invention is to overcome the difficulties in the fabrication of diamond thin films mentioned heretofore. A particular object of the invention is to provide a method of making a diamond thin film that will be characterized by high thermal conductivity, large band gap, and high electron mobility, or the properties that are desired for electronic devices.
It has now been found that the aforementioned objects can be attained by subjecting a substrate immersed in a liquid containing carbon and hydrogen to a laser pulse.
A diamond thin film is prepared according to the invention in the following manner.
A silicon substrate is immersed in methanol. The methanol is contained in a vessel which has a quartz window. An excimer laser pulse, with wavelength of 248 nanometers (nm) and pulse duration of about 20 nanoseconds (ns) is propagated through the quartz window and through the methanol. This laser pulse is intercepted by the silicon substrate. This substrate is heated by absorption of the laser pulse. The methanol in contact with the heated substrate is pyrolyzed. Carbon material from the pyrolyzed methanol then grows on the substrate, and the high density of hydrogen reacts with and removes from the substrate any carbon which does not have diamond bonds.
Repeated application of the laser pulse continues growth of the diamond film.
Diamond films prepared by this method are less expensive and simpler to produce due to the simpler processing equipment required and lower total power consumed.
In lieu of the silicon substrate, any substrate can be used that is absorptive to the laser light used.
In lieu of the excimer laser disclosed in the preferred embodiment, one might use another pulsed laser which has the following properties:
the substrate used can be heated by the laser to about 1000° C., with each laser pulse; and the liquid and window used are transparent to the laser pulse.
In lieu of the methanol disclosed in the preferred embodiment, any liquid that contains both carbon and hydrogen and that is transparent to the laser pulse can be used in the invention. Included within the scope of the invention as the liquid is the use of benzene, ethanol, acetic acid, toluene, etc.
In the preferred embodiment the growing film can be easily doped during growth to provide desired n, or p type semi-conducting behavior. This is done by introducing dopant elements into the liquid prior to subjecting the substrate to the laser pulse.
The method of the invention is believed to work because it produces partial pressures of carbon and hydrogen and temperatures that are known to favor diamond (SP3 bonding of carbon) growth.
I wish it to be understood that I do not desire to be limited to the exact details of construction as described for obvious modifications will occur to a person skilled in the art.
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|US5225926 *||Sep 4, 1991||Jul 6, 1993||International Business Machines Corporation||Durable optical elements fabricated from free standing polycrystalline diamond and non-hydrogenated amorphous diamond like carbon (dlc) thin films|
|US5273788 *||Jul 20, 1992||Dec 28, 1993||The University Of Utah||Preparation of diamond and diamond-like thin films|
|US5334283 *||Aug 31, 1992||Aug 2, 1994||The University Of North Carolina At Chapel Hill||Process for selectively etching diamond|
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|US20020169114 *||Jan 25, 2002||Nov 14, 2002||The United States Of America, Represented By The Secretary, Department Of Health And Human Services||Formulation of boronic acid compounds|
|US20040208817 *||Aug 26, 2002||Oct 21, 2004||Michael Elbaum||Direct surface patterning of carbon|
|US20090123657 *||Mar 27, 2006||May 14, 2009||Hitotoshi Murase||Process for Producing an Amorphous Carbon Film|
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|U.S. Classification||427/554, 427/430.1, 427/443.2, 427/559|
|International Classification||C30B25/10, C30B7/00|
|Cooperative Classification||C30B25/105, C30B7/00, C30B29/04|
|European Classification||C30B25/10B, C30B7/00|
|Jun 18, 1990||AS||Assignment|
Owner name: UNITED STATES OF AMERICA, THE, AS REPRESENTED BY T
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:NEIFELD, RICHARD A.;REEL/FRAME:005340/0359
Effective date: 19891214
|Apr 11, 1994||SULP||Surcharge for late payment|
|Apr 11, 1994||FPAY||Fee payment|
Year of fee payment: 4
|Apr 12, 1994||REMI||Maintenance fee reminder mailed|
|Mar 31, 1998||REMI||Maintenance fee reminder mailed|
|Sep 2, 1998||SULP||Surcharge for late payment|
|Sep 2, 1998||FPAY||Fee payment|
Year of fee payment: 8
|Mar 19, 2002||REMI||Maintenance fee reminder mailed|
|Sep 4, 2002||LAPS||Lapse for failure to pay maintenance fees|
|Oct 29, 2002||FP||Expired due to failure to pay maintenance fee|
Effective date: 20020904